docs: def allowed_to_preview(user):
      """
      Is the user allowed to view the preview?
  
      Users are only allowed to view the preview if they are authenticated, active and staff.
  
      :param user: A User object instance.
      :return: Boolean.
      """
      if (
          user.is_authenticated and
          user.is_active and
          user.is_staff
      ):
          return True
      return False